<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
			var a = "123";
			var b = "456";
			document.write(a + b);
			document.write("<br />");

			var c = parseInt(a);
			var d = parseInt(b);
			document.write(c + d);
			document.write("<br />");

			document.write('isNaN("abc")=' + isNaN("abc"));
			document.write("<br />");
			document.write('isNaN("123")=' + isNaN("123"));
			document.write("<br />");

			document.write(1 / 0);
			document.write("<br />");
			document.write(isFinite(1 / 0));
			document.write("<br />");

			str = "3+5";
			document.write(eval(str));
			str = "alert('Hello world!')";
			//eval(str);
			document.write("<br />");
			var str2 = "https//www.baidu.com/?s=java习题";
			var str3 = encodeURI(str2);
			document.write("<br />");
			document.write(str3);
			var str4 = decodeURI(str3);
			document.write(str4);
			document.write("<br />");
		</script>
	</body>
</html>
